The Precambrian basement rocks of Ohio became part of the North American continent
A) more than 2.5 billion years ago.
B) 1.9 billion years ago.
C) 1.8 to 1.9 billion years ago.
D) 1.7 to 1.8 billion years ago.
E) about 1.1 billion years ago.
Question 2
How fast do mountains rise?
A) 3 to 10 mm per year
B) 1 to 10 cm per year
C) 1.5 cm per year
D) As fast as finger nail growth.